Dental engine



June 24, 1941 w. H. NITSCHKE DENTAL ENGINE Filed Feb. 14, 1940 ATTORNEYSPatented June 24, 1941 UNITED STATES PATENT orrlce 2,246,530 DENTALENGINE Wiiliam H. Nitschke, New York, N. Y. Ap eas ment,14,1940,SerialNo. 318,825

2- Claims.

, This invention relates to a novel and improved form. of dental engine,the novel features ,of which will be best understood from the followingdescription and the annexed drawing, in which I have shown a selectedembodiment of the in.- vention and in which:

Fig. 1 is an elevation of so much of the dental engine as is necessaryto an understanding of the invention; Fig. 2 is a view on the same planeasFig. 1,,but showing only parts of the engine and on an enlarged scale;

I Fig, 3 is, a fragmentary view showing a different arrangement of aspring than oneof the springs shown in Figs. 1 and 2.

The invention will be described and defined, for convenience, asembodied in what is usually called a dental engine, but by thatexpression I intend to include all similar apparatus, for example thatsometimes referred to as a surgical engine.

The engine comprises the usual motor I having a shaft 2 over which runsa belt 3 which engages various pulleys and finally runs over a pulley 5on a hand piece 6 which carries the tool I. The motor I is carried on astandard 8 of any usual or suitable construction and upon which iscarried a support 9 which may be pivoted as at II], to an arm I0 securedto the casing of the motor I and extending upwardly therefrom. However,the

support 9 is sometimes secured in fixed position and may be consideredas relatively fixed, although it may be adjusted on its pivot III, ormay be balanced thereon with a counterweight.

At the forward end of the support 9, there is provided a pivot I I onwhich is pivoted an arm I2 which, for the sake of convenience, I shallrefer to as the upper arm. This arm depends from the pivot I I aboutwhich it may swing freely, and at its lower end is provided with a pivotI3 on which freely swings the fore arm I4 of the engine. The hand piece6 may be secured to the front end of the fore arm I4 by a suitable wristpiece I5, the details of which are not necessary to an understanding ofthe invention and consequently will not be described.

The structure described above is more or less conventional and, asknown, the engine is operated by the dentist holding the hand piece inone hand, somewhat in the way that a pencil is held, usually the handpiece resting upon the crotch between the thumb and the fore finger, andthe front part of the hand piece being engaged by the tips of the thumband fore finger, in the same manner that a pencil is engaged whenwriting. Usually, the weight supported by the hand of the dentist is onthe order of seven ounces, although this weight may vary somewhat withdifferentengines. However, there is always a constant weight to besupported by the hand of the dentist, and this weight is enough to tirethe hand of the dentist and thus possibly interfere with the accuracy ofthe work which he is doing With the tool in his. hands.

The weight is felt on the rear end of the hand piece 6 and thus tends topivot the hand piece about the point where it is supported on the handof the dentist. If the hand piece is not carefully held at all times,the weight of the engine thus may cause a movement of the hand piece andconsequently of the tool, which may cause inaccurate work.

I have found that I can overcome the above difficulties and canpractically balance the engine in such a way that there is practicallyno weight applied at the rear of the hand piece, and the pull drag isgreatly diminished. For example, in one test made by me, I found that Ihad reduced the weight at that point from seven ounces to one ounce and,by careful adjustment,

it can be entirely eliminated. This result I have achieved by thefollowing construction:

Connected to the support 9 and the upper arm I2 is a spring, here shownas a tension spring I6,

which may be secured at one end to a clamp I'I on the support 9 and atthe other end to a rod I8 which may be secured by a clamp I9 to theupper arm I2, this rod forming an extension of the arm I2 extending pastthe pivot II as shown. The tension of the spring may be adjusted bysecuring one end of it to an eye-bolt 2'0 threaded into engagement withthe clamp II.

Preferably I also use another spring 2| which may be secured at one endto a clamp 22 on the upper arm I2 and at the other end to a clamp 23 onthe fore arm I4. The tension of the spring may be adjusted by a turnbuckle 24.

By the above arrangement, the weight of the fore arm, wrist piece, andhand piece may be taken up by the spring 2| and transferred in largemeasure to the upper part of the upper arm I2, particularly when theupper arm I2 is approximately vertical. However, when the engine is inuse, this arm is often pulled out of the vertical so that the lower endis not directly under the pivot II and the more this arm departs fromthe vertical, the greater is the proportion of its weight which has tobe supported by the hand of the dentist, and more specifically thegreater is the weight which tends to tip the hand piece in the dentist'shand. However, by using the spring I6 and arranging it in such a Waythat a great part of the weight of the upper arm I2 is transferred tothe support 9, it will be seen that even when the upper arm is notvertical, its weight or at least the component thereof, which otherwisewould be felt on the dentists hand, is instead transferred to thesupport. Thus no matter what may be the position of the upper arm or forthat matter of the fore arm, the balanced condition is maintained sothat there is no appreciable weight felt at the rear end of the handpiece 6. Therefore, no matter What may be the position of the engine, orrather of the arms I2 and I4, the hand piece is balanced so that thedentist does not have to overcome any weight or tendency to tip the handpiece in his hand.

In Fig. 3, I have shown the pivoted connection between the arms I2 and Mand have shown a spring 25 coiled about the pivot I3 connecting thosearms and transferring some of the weight of the arm I4 to the arm I2. Inthis form, as in the form shown in Figs. 1 and 2, it will be seen thatthe spring It will create a tendency for the arm I2 to rotate in acounterclockwise direction about the pivot I I, whereas the spring 2| or25, as the case may he, would tend to cause a similar rotation of thearm It about the pivot I3.

This invention may be made an integral part of the dental engine and isapplicable to all engines of this type, such as the surgical engine.

While I have shown the invention as embodied in a. specific form, it isto be understood that various changes in details may be made withoutdeparting from the scope of the invention as de fined by the appendedclaims.

I claim:

1. In a motor driven tool of the class described, a support and an upperarm hanging from said support, a fore-arm hanging from said upper arm ona horizontal pivot upon which it is movable to any angular position withrespect to the upper arm Without bodily displacement of said pivot, ahand piece secured at its rear end on the free end of said fore-arm, anda spring acting between said upper arm and fore-arm and tending torotate the fore-arm on its pivot to raise said fore-arm and thus balancethe hand piece in the hand of the operator by relieving the downwardpull of the fore-arm on the rear end of the hand piece.

2. In a motor driven tool of the class described, a support and an upperarm hanging from said support on a horizontal pivot upon which it ismovable to any angular position with respect to the support withoutbodily displacement of the pivot, a fore-arm hanging from said upper armon a horizontal pivot upon which it is movable to any angular positionwith respect to the upper arm without bodily displacement of saidlastnamed pivot, a hand piece secured at its rear end on the free end ofsaid fore-arm, a spring acting between said upper arm and fore-arm andtending to rotate the fore-arm on its pivot to raise said fore-arm andthus balance the hand piece in the hand of the operator by relieving thedownward pull of the fore-arm on the rear end of the hand piece, and asecond spring acting between said support and said upper arm and tendingto rotate the upper arm on said pivot on the support, to move the lowerend of said upper arm forwardly.

WILLIAM H. NITSCHKE.

